I CANT CHANGE THE TAX RATE

press AC
while holding AC press SET/%
while holding SET/% release AC
your screen should read SET on top
now press TAX+(TAX RATE)
enter tax rate (7.25 or 8.75) what ever the tax rate
then press the SET% again,
you just changed your tax rate

1. Press [AC]
2. Hold [SET/%] key for about 2 seconds
3. Press [TAX+]
4. Input the tax rate
5. Press [SET/%]

The above worked for my MS-80TV. I did have to do it a couple times. I noticed when I did it the time it worked I could see the word "SET" in the display. I think the key might be to hold the set button just until you see the word SET.

Best Wishes!